The innate immune system of mammals is designed to distinguish between endogenous and exogenous structures. As soon as exogenous structures are exposed they will be recognised by the innate immune system and a number of defence systems are recruited and initiated, which may lead to accelerated activation of coagulation and inflammation. The blood vessels are covered by endothelial cells which express heparan sulphate (a heparin-like substance) at the outermost layer. Like heparin, heparan sulphate exhibits carbohydrate regions capable of accelerating the inhibitory effect of antithrombin. Due to pathological processes that may be initiated by e.g. lack of oxygen (ischemia), mechanical damage, etc., the chemical and biological constitution of the involved tissue may be changed so that the tissue will be recognised as exogenous. In the area of tissue engineering, isolation and processing of cells (as e.g. islets of Langerhans) may lead to exposure of exogenous structures when such cells are transfused to blood, consequently leading to loss of biological function, and even destruction, of the cells due to instant blood mediated inflammatory response (IBMIR), (Diabetes, vol. 48, 1907-1914, 1999)